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Cardiac contractility modulation (CCM) is a
device-
based therapy for the treatment of systolic left
ventricular chronic heart failure. Unlike other device
-
based therapies for heart failure, CCM delivers non
-
excitatory pacing signals to the myocardium. This leads to
an extension of the action potential and to an improved
contractility of the heart. The modeling and simulation
was done with the electromagnetic simulation software
CST. Three CCM electrodes were inserted into the
Offenburg heart rhythm model an
d subsequently
simulated the electric field propagation in CCM therapy.
In addition, simulations of CCM have been performed
with electrodes from other device
-based therapies, such as
cardiac resynchronization therapy (CRT) and implantable
cardioverter.
/. defi
brillator (ICD) therapy.
At the same
distance to the simulation electrode, the electric field is
slightly stronger in CCM therapy than in CCM therapy
with additionally implanted CRT or ICD electrodes. In
addition, there is a change in the electric field pr
opagation
at the electrodes of the CRT and the shock electrode of the
ICD.
By simulating several different therapy procedures
on the heart, it is possible to check how they affect their
behavior during normal operation. CCM heart rhythm
model simulation al
lows the evaluation the individual
electrical pacing and sensing field during CCM.

Pulmonary vein isolation (PVI) is a common
therapy in atrial fibrillation (AF). The cryoballoon was
invented to isolate the pulmonary vein in one step and in a
shorter time than a point-by-point radiofrequency (RF)
ablation. The aim of the study was to model two cryoballoon
catheters, one RF catheter and to integrate them into a heart
rhythm model for the static and dynamic simulation of PVI
by cryoablation and RF ablation in AF. The modeling and
simulation were carried out using the electromagnetic and
thermal simulation software CST (CST, Darmstadt). Two
cryoballons and one RF ablation catheter were modeled
based on the technical manuals of the manufacturers
Medtronic and Osypka. The PVI especially the isolation of
the left inferior pulmonary vein using a cryoballoon catheter
was performed with a -50 °C heatsource and an exponential
signal. The temperature at the balloon surface was -50 °C
after 20 s ablation time, -24 °C from the balloon 0,5 mm in
the myocardium, at a distance of 1 mm -3 °C, at 2 mm 18 °C
and at a distance of 3mm 29 °C. PVI with RF energy was
simulated with an applied power of 5 W at 420 kHz at the
distal 8 mm ablation electrode. The temperature at the tip
electrode was 110 °C after 15 s ablation time, 75 °C from the
balloon at 0,5 mm in the myocardium, at a distance of 1 mm
58 °C, at 2 mm 45 °C and at a distance of 3 mm 38 °C.
Virtual heart rhythm and catheter models as well as the
simulation of the temperature allow the simulation of PVI in
AF by cryo ablation and RF ablation. The 3D simulation of
the temperature profile may be used to optimize RF and cryo
ablation.